It is generally desirable in audio devices to be able to orient the directional gain of a microphone in the direction of a desired source. This permits audio from the desired source to be emphasized and audio from non-desired sources to be de-emphasized. Assuming the microphone has directivity, one way to orient its directional gain is to physically rotate the microphone.
If the audio device has an array of microphones, a signal processor can combine and process audio signals from these microphones so as to emphasize audio signals representing sound from the desired source and de-emphasize audio signals from non-desired sources. This process is referred to as “beam forming.” The signal processor can also change the emphasis of the audio signals. This change is referred to as “beam steering.” The concepts of beam forming and beam steering can also be expressed by the term “virtual microphone.” The “orientation” of the virtual microphone is the direction of the beam, and the processes of “orienting” or “reorienting” the virtual microphone are carried out by beam steering.
The purpose of forming a virtual microphone is to give the physical array directivity (directional sensitivity) or other desirable characteristic. By forming a virtual microphone, the physical microphones need not be physically moved in order to reorient their directional gain. Rather, the virtual microphone is reoriented.